Apparatus for making netlike structures of curved construction

ABSTRACT

Apparatus for making netlike structures of curved construction in which composite extrusion nozzles are each turned through an angle of 180* alternately with relative movement between nozzle sections along arcuate paths extending about a common center.

United States Patent Theodore H. Fairbanks West Chester, Pa. 848,009

Aug. 6, 1969 Aug. 31, 1971 FMC Corporation Philadelphia, Pa.

Inventor Appl. No. Filed Patented Assignee APPARATUS FOR MAKING NETILJIKE STRUCTURES OF CURVE!) CONSTRUCTION 7 Claims, 5 Drawing Figs.

U.S. Cll 18/12 IN, 264/103, 264/167, 264/DIG. 81

Int. Cl B2911 3/00 1 Field ofSearch 18/12 N, 13

K; 264/103, 167, DlG. 81

[56] References Cited UNITED STATES PATENTS 3,012,275 12/1961 Nalle 18/12 3,331,903 7/1967 Mine 18/12 Primary Examiner-J. Spencer Overholser Assistant Examiner-L. R. Frye Att0rneysThomas R. OMalley, George F. Mueller and Eugene G. Horsky ABSTRACT: Apparatus for making netlike structures of curved construction in which composite extrusion nozzles are each turned through an angle of 180 alternately with relative movement between nozzle sections along arcuate paths extending about a common center.

PATENTEU AUG3I IQYi 3,601,850

AlPlPAlitA'lilUfi lFtOlit MAlltllNG NETlLlilltilE STRUCTURES 01F ClUhi/lrlll) lCOhlfilllhlJCTllON The present invention is directed to an apparatus for making netlike structures of curved construction having strands which are disposed in twisted and/or woven or braided relationship.

US. Pat. No. 3,331,903 discloses a method and apparatus for making a net from plastic material by extruding a plurality of pairs of filaments of plastic material in such a manner that the filaments in each pair are spaced from each other in a first direction and the pairs of filaments are spaced from each other a given distance in a second direction. The filaments of each pair of filaments are revolved, at the moment of their extrusion and before being solidified, about an axis extending between the filaments of each pair of filaments so as to twist the filaments of each pair together and to thus integrally connect the same. One of the filaments of each pair offilaments is then moved in a second direction a distance equal to the spacing between pairs of filaments while continuing the extrusion of the filaments, after which the pairs of filaments are again revolved as heretofore described. By continuously repeating the above steps and setting the extruded filaments of plastic material, a net is provided.

The above-noted United States patent is concerned primarily with a method and apparatus for making a flat net, but does suggest that the teachings set forth therein are adapted also for making a tubular net. Of importance, however, is that regardless of the shape of the net produced the filaments forming such net are revolved through one or more complete revolutions as they are extruded and while they are still in a plastic condition so as to twist and integrally connect or bond the same to each other at their locations of twisting.

A primary object of this invention is to provide a generally new or improved and more satisfactory apparatus for making netlike structures of curved or tubular construction by extrusion.

Another object of this invention is a new or improved apparatus for making, by extrusion, continuous woven or braided netlike structures of curved or tubular construction.

Still another object is the provision of an apparatus for making, by extrusion, woven or braided netlike structures of curved construction having a variety of interlaced strand or filament patterns.

These and other objects are accomplished in accordance with the present invention by an apparatus in which a plurality of pairs of continuous streams of fiowable strand-forming material are extruded in spaced relationship, with the streams in each such pair being located along opposite sides of a common are or circle. The streams of at least some and preferably all pairs of streams are turned through an angle of only 180 or further multiple of 180 about an axis extending between the respective streams of each such pair of streams. Once turned, the streams of each such pair of streams are moved relatively in directions concentric with the arc or circle along which they are extruded to arrange at least certain of the streams of each pair of streams into different pairs. The streams of strand-- forming material are set concomitantly with their extrusion, either prior to or after contact therebetween. By continuous extrusion of the streams of strand-forming material, and net" like structure of curved or tubular construction is produced.

The streams of each pair of streams need not be spaced equal distances from the common arc or circle along which they are extruded, not is it essential that the spacing between streams of all such pairs of streams be the same. The plurality of pairs of streams may be disposed generally along an arc of 360 or less, preferably with the axes about which the respective pairs of streams are turned being spaced equal angular distances from each other.

Relative movement of the streams of at least some and preferably all pairs of streams is effected, desirably but not necessarily, by moving the streams of each such pair of streams oppositely of each other in directions concentric with the are or circle along which they are extruded. During such movement the streams of each pair ofstreams may be moved a distance equal to one-half of the angular spacing between adjacent pairs of streams or a further multiple thereof. It will be apparent that this relative movement of the streams of each such pair of streams may be varied either periodically or randomly throughout the method, providing it is a multiple of one-half of the given distance between the adjacent pairs of streams, to provide netlike structures with different strand patterns along their lengths.

When the plurality of pairs of streams are disposed generally along an arc of less then 360, it is essential that the direction in which the pairs of streams are turned be reversed after each relative movement of the streams of such pairs, and that the direction of movement of the respective streams of each pair of streams during the relative movement thereof be reversed after each turning of the pairs of streams. This same procedure may be employed but is not essential when the plurality of pairs of streams are extruded at spaced intervals along an arc of 360. in this latter array of streams, the pairs of streams may be turned 180 in the same direction after each relative movement between streams of such pairs, provided there is no reversal in the direction in which corresponding streams of the different pairs of streams are moved during their relative movement.

in the resulting netlike structure, the stands will be interlaced with each other in a woven or braided construction, or

may be twisted together, depending upon the angle through which the streams forming such strands were turned during and/or following their extrusion. Setting of the extruded streams into strands may be effected prior to any contact between the extruded streams whereby the strands in the resulting netlike structurewould be unbonded at their locations of crossing. Alternatively, the extruded streams may be set into strands after such streams have made contact with each other so that the strands in the resulting netlike structure would be bonded to each other at their locations of crossing.

The apparatus of the present invention includes a plurality of composite nozzles each including a pair of like extrusion sections and a spacer section positioned therebetween. The nozzle extrusion and spacer sections are formed with mating arcuate walls with the arcuate walls of all extrusion sections being of like radius. These extrusion sections are supported in spaced'apart relationship with an arcuate wall of one such section of each of the plurality of nozzles extending along a common are or circle having a radius equal to that of such arcuate walls.

Means are provided for intermittently turning nozzles through an angle of only or further multiple of 180 about an axis located midway between the arcuate walls of the extrusion sections of such nozzles, and also for relatively moving the extrusion sections of each of the nozzles to rearrange, the same into alignment with like extrusion sections of other of such nozzles. The means for effecting relative movement of the nozzle sections is operative alternately with the nozzle turning means and serves to move corresponding extrusion sections of the respective nozzles simultaneously and in the same direction along paths concentric with the common arc or circle.

At least on orifice extends through each of the nozzle extrusion sections and means are provided for delivering flowable strand-forming material to such orifices. Means are also provided for setting the streams of strand-forming material which are extruded from the orifices in the nozzle extrusion sections.

The arcuate walls of the nozzle extrusion sections may be of either convex or concave configuration, with the walls of the spacer sections being shaped to mate therewith. The apparatus may include at least one pair of nozzles in which the extrusion sections have arcuate walls of concave configuration. While the arcuate walls of all of the nozzled extrusion sections must be of like radius, such radius may be varied; the smaller the radius, the more pronounced is the curvature of the resulting netlike structure.

In the apparatus of the present invention for making tubular netlike structures, the nozzle supporting means include a pair of concentricannular members, one of which is disposed with its outer peripheral surface slidably engaging with the inner peripheral surface of the other of such annular members. Cooperating recesses are formed along the contacting peripheral surfaces of the annular members and together define openings in which the composite nozzles are rotatably carried. In such apparatus, at least one of the annular members is driven, after each turning of the nozzles, in-a direction which is the same or opposite to its prior movement. As heretofore mentioned, reversal in the direction of relative movement of the nozzle extrusion sections requires that the direction of nozzle turning also be reversed.

Tubular netlike structures formed the apparatus of the present invention are particularly suited for use in the packaging of produce, such as potatoes, onions, etc. Netlike structures having a curvature of less than 360, say 180 or 270, may be combined to provide corrugated members which are suitable for use, for example, as shock absorbing insulation means.

The teachings of the present invention are applicable for use with a variety of materials, which are referred to by the terms plastic" or strand-forming materials, including materials which are thermoplastic, such as polyamides or su. perpolyamides, polyesters, polyvinyl chloride, copolymers thereof, polyolefins, cellulose acetates, etc., natural or synthetic rubbers, thermosetting materials or wet-spinnable materials, such as viscose, cupro-ammonium cellulose, or carboxymethyl cellulose. Such materials may include various additives, such as stabilizers, dyes, foaming agents, etc., if so desired. It will be apparent that the manner by which the extruded streams are set will depend upon the particular plastic or strand-forming material which is being employed.

For a greater understanding of this invention, reference is made to the following detailed description and drawing in which;

FIG. 1 is a diagrammatic view showing a portion of an apparatusemploying teachings as suggested by U.S. Pat. No. 3,33I,903; I

FIG. 2 is a view similar to FIG. 1 of a modified apparatus;

FIG. 3 is a view similar to FIG. 1 illustrating nozzles employed in the apparatus of the present invention;

FIG. 4 is a partial plan view of the apparatus of the present invention; and

FIG. 5 is a section taken vertically through the apparatus shown in FIG. 4.

As heretofore mentioned, U.S. Pat. No. 3,331,903 discloses a method and apparatus for making nets by extruding filaments of plastic material and periodically twisting such extruded filaments with each other one or more complete revolutions while they are still in a tacky condition to thus provide integral filament junctions.

More specifically, the apparatus described in the above U.S. patent includes two sets of nozzle members, each having a periphery defined by a semicircular wall and a flat wall, and each being formed with a bore for extruding a filament therethrough. The nozzle members in each set are spaced from each other a given distance and the nozzled members in the two sets are respectively arranged closely to each other to form pairs of adjacent nozzle members. Means are provided for revolving each pair of nozzle members about an axis located between the bores thereof and for shifting the nozzle members of one set through the given distance of spacing so that each nozzle member of the one set is again closely arranged to a respective nozzle member of the other set to form a pair of adjacent nozzle members.

In the apparatus specifically described and illustrated in U.S. Pat. No. 3,331,903 the two sets ofnozzle members are arranged in straight rows. The patentee does suggest, however, that it is also possible to arrange such sets of nozzle members along two concentric circles. This latter arrangement is illustrated in FIG. 1 of the accompanying drawing wherein nozzle members 11 of one set and nozzle members 13 of a second set are carried by annular supports 15 and 17, respectively. The periphery of eachnozzle member of both such sets is defined by a semicircular wall 19 and a flat wall 21, and each such members is provided with and extrusion bore 23.

In accordance with the method described in the abovenoted U.S. patent, plastic material would be delivered to each of the noule members 11 and 13 of both sets of such nozzle members and would be extruded from the bores 23 as filaments. The nozzle members of the two sets, being aligned in pairs, would then be revolved through one or more complete revolutions by suitable means, not shown.

Continuing with the method as disclosed in the above-cited patent, one set of nozzle members would now be shifted so as to rearrange the nozzle members of such one set with different nozzle members of the other of such sets. It will be noted, however, that portions of the nozzle members 13 of one such series project beyond the inside peripheral wall 25 of the annular support 15 and thus neither of the annular supports 15 or 17 can be moved about its axis. Shifting of the nozzle members of one set of nozzle members relative to the other set thereof, as is required in the method disclosed in the cited patent, cannot be achieved and the apparatus shown in FIG. 1 of the accompanying drawing is considered inoperative.

While not disclosed nor suggested in the above-noted U.S. patent, the apparatus shown in FIG. 1 of the accompanying drawing may be modified to render the samecapable of making net structures. As shown in FIG. 2 of the drawing, tow sets of nozzle members 27 and 29 are carried by annular supports 31 and 33, with each nozzle member having an extrusion bore 35. These twosets of nozzle members differ from those shown in FIG. 1 in that the nozzle members 27 of one such set are each formed with an arcuate wall 37 which mates with an arcuate wall 39 formed on each of the nozzle members 29 of the other of such sets. The arcuated walls 37 and 39 of the nozzle members are of like radius, which is equal to that of the peripheral walls 41 and 43 of the annular supports 31 and 33, respectively.

In using the apparatus shown in FIG. 2 of the accompanying drawing, pair of aligned nozzle members must be revolved one or more complete revolutions alternately with the shifting of one set of nozzle members relative to the other of such sets to rearrange the same into different pairs. When revolved, it is essential that the pairs of nozzle members of this apparatus be turned through one or more complete 360 revolutions. Failure to observe this limitation will render the apparatus of FIG. 2 inoperative. For example, moving the pairs of 'nozzle members through an angle of only or furtherodd number multiple of 180 would dispose the nozzle members as shown at the lowermost portion of FIG. 2. In this position of the nozzle members, neither of the annular supports 31 and 33 is capable of turning about its axis and thus shifting of one set of nozzle members relative to the other of such sets could not be achieved.

From the above description it is believed clear that the apparatus shown in FIG. 1, which corresponds with that suggested in U.S. Pat. No. 3,331,903, is inoperative while the apparatus shown in FIG. 2 is adapted to provide only net structures having integral junctions at which filaments are twisted together through one or more turns.

The apparatus of the present invention is also capable providing nets as formed by the apparatus shown in FIG. 2 but, more important, is adapted for use in the manufacture of netlike structures of curved or tubular construction in which strands or filaments are interlaced with each other in a woven or braided relationship.

Referring to FIGS. 3-5 of the drawing, the apparatus of the present invention includes a pair of concentric cylinders 45 and 47 which are held in fixed positions by suitable supporting structures, not shown. At their lowermost ends, the cylinders 45 and 47 each include an integral flange 49 and 51, respectively, on which are slidably carried a pair of concentric, annular nozzle support members 53 and 55. Split rings 57 and 59 are seated within grooves 61 and 63 formed in opposing walls 65 and 67 of the cylinders 45 and 47, respectively, and serve to retain the annular members 53 and 55 against the cylinder flanges.

At least one of the annular members 53 and 55 is adapted to be rotated or oscillated about its axis and in the preferred construction both such members 53 and 55 are capable of rotation. As shown in FIG. 5, gear teeth 69 are machined into the bottom wall 71 of the annular member 53 at a location adjacent to its outer periphery, while like gear teeth 73 are formed in the bottom wall 75 of the annular member 55 but adjacent to its inner periphery. One or more openings 77 are provided in each of the cylinder flanges 49 and 51 for accommodating gears 79 and 81 which mesh with the teeth 69 and 73, respectively, formed in the annular members 53 and 55. The gears 79 and 81 are fixed, respectively, to shafts 03 and 85 which pass through openings 07 in the cylinders 45 and 47 and are intermittently driven by suitable means, not shown.

Opening along contacting peripheral surfaces 89 and 91 of the annular members 53 and 55 are recesses 93 and 95, respectively, which are of like radius and, when aligned with each other, together define circular openings within each of which is disposed a composite,,circular nozzle. As more fully described hereafter, the composite nozzles are retained within the aligned recesses in the annular members 53 and 55 by flange portions formed along the uppermost ends thereof.

In FIG. 3 are illustrated various forms of composite nozzles 97, 99 and 101 which are suitable for use in the apparatus of the present invention. The nozzles 97, 99 and 101 all include a pair of like extrusion sections 103, each having arcuate walls 105 and 107, and the spacer section 109 having like arcuate walls 111 which mate with the walls 107 of the extrusion sections. The arcuate walls 105 of the nozzle extrusion sections 103 are of a radius substantially equal to that of the recessed 93 and 95 in the annular members 53 and 55, while the walls 107 thereof are of a radius substantially equal to that of the peripheral surfaces 89 and 91 of the annular members 53 and 55. Common also to each of the different forms of nozzles 97, 99 and 101 is at least one orifice 113 extending through each of the extrusion sections 103.

The composite nozzles 97, 99 and 101 are of like circular cross section and differ only in the size and/or shape of the sections thereof. More particularly, the spacer section 103 of the nozzles 97 and 99 are of like configuration and differ only in size. Thus the spacer section 109 of the nozzle 97 is larger than the spacer section 109 of the nozzle 99 and includes also arcuate walls 115 which form part of the nozzle periphery. On the other hand, the nozzle 101 differs from the nozzles 97 and 99 in that the arcuate walls 107 of extrusion sections 103 are of convex configuration while the mating walls 111 of its spacer section 109 are concave in shape. The spacer sections 109 of the nozzle 101 also includes arcuate walls 117 which form part of the nozzle periphery.

The plurality of nozzles employed in the apparatus of the present invention may be alike. Alternatively, the nozzles may differ in size and/or shape. For example, at least one pair of each of the different nozzles may be present in the same apparatus. For simplicity and ease of description, all composite nozzles employed in the apparatus shown in FIGS. 4 and 5 are of like size and shape and correspond to nozzles 97 shown in FIG. 3.

The nozzles 97 each include flange portions 119 and 121 projecting from the extrusion and spacer sections, respectively, which are adapted to rest upon the top surfaces of the annular members 53 and 55. Each of the nozzles 97 is adapted to be periodically turned about its axis through an angle of only I80", or further multiple thereof, and for this purpose are provided with gear teeth 123. Ring gears 125 and 127 mesh with the teeth 123 on the nozzles 97 and, when driven, serve to turn all of the nozzles simultaneously and in the same directions.

The flanges 49 and 51 of the cylinders 45 and 47 are recessed at 129 and 131, respectively, to retain the ring gears 125 and 127 in position yet permit free sliding movement thereof. The ring gears and 127 are moved in a sequence, as hereafter described, by gears 133 and 135 which are fixed to shafts 137 and 139. Suitable means, not shown, are provided for intermittently driving the shafts 137 and 139 and for carrying such shafts and their driving means with the respective annular members 53 and 55 so as to avoid imparting any turning movement to the nozzle sections while such annular members are being moved relative to each other.

With the various elements of the apparatus in a starting position as shown in FIG. 4 and 5, a flowable strand-forming material, such as a molten thermoplastic material, is delivered in-between the cylinders 45 and 47, as through a conduit 141. Such flowable strand-forming material is delivered under pressure and is extruded from the nozzle orifices 113 as continuous streams 143 which are set in a liquid 145, which may be cool water.

All of the nozzles 97 are simultaneously turned in the same direction and through an angle of or further multiple thereof by the ring gears 125 and 127 which are rotated in opposite directions about their common axis by driving the shafts 137 and 139 in opposite directions. The annular members 53 and 55 are held stationary during the turning of the nozzles 97 and, once such turning is completed, the nozzles remain stationary while relative movement is effected between the annular members 53 and 55.

The purpose of relative movement between the annular members 53 and 55 is to rearrange or pair the respective extrusion members 53 and 55 is to rearrange or pair the respective extrusion sections 103 of the individual nozzles 97 with extrusion sections of other of such nozzles alternately with the turningof the nozzles sections about their respective axes. Thus, such relative movement may be provided by rotating either one of the annular members 53 and 55 about its axis or by rotating both of such annular members in the same direction but at different rates of speed or in opposite directions.

Shifting of the member and/or the member 55 is achieved by driving the gear 79 and/or the gear 01 which are in meshing relationship with the teeth 69 and 73 formed in the bottom walls 71 and 75 of the respective annular members. As heretofore mentioned, the ring gears 125 and 127 and their driving means are supported so as to shift with the respective annular members 53 and 55 and thereby insure that no torque is applied to the nozzle sections during this shifting movement.

The degree of relative movement between the annular members must be at least such as to shift an extrusion section 103 of the individual nozzles 97 into alignment with an extrusion section 103 of a nozzle directly adjacent thereto. For example, if only one of the annular members 53 and 55 is shifted, it would be moved through an angle equal to at least the original angular spacing between the axes of adjacent nozzles, as measured along the surfaces 09 and 91 of such members. Such one annular member may be moved through a distance equal to a multiple of such angle and such distance may be varied through the method to vary the strand pattern in the resulting netlike structures. Of course, if the apparatus includes nozzles having sections of different size and/or sections of different shape, as for example nozzles 97 and 101 shown in FIG. 3, the relative movement between the annular members 53 and 55 must be such as to insure that like nozzle extrusions are paired with each other.

Assuming, for purposes of description, that the annular members 53 and 55 are both shifted in opposite directions relative to each other, the distance such members are moved must be at least equal to one-half of the angular spacing between the axes of adjacent nozzles, as measured along the surfaces 89 and 91 of such surfaces. It will be noted from FIG. 4 that during this shifting of the annular members 53 and 55, one of the extrusion sections 103 of each nozzle 97 will move with the annular member 53 while the other of extrusion sec tion 103 and spacer section 109 of each such nozzle will travel with the annular member 55.

After this rearrangement of the nozzle sections, the annular members 53 and 55 are again held stationary while the nozzles 97 are again turned through an angle of-l80or further multiple thereof in a direction which is either the same or opposite to that of their prior turning movement. Following this turning of the nozzles 97, relative movement between the annular members 53 and 55 is again effected.

The angle through with the nozzles 97 are turned is important both from the standpoint of the netlike structure produced and the practice of the method itself. For example, if the nozzles 97 of the illustrated apparatus are turned through an angle of 360 or further multiple of 180, the strands formed by the streams of strand-forming material extruded from the orifices 113 will be twisted together at their locations of crossing. in this instance no special care need be taken in the direction in which the nozzles are turned, providing all are turned in the same direction. Similarly, each shifting of the annular members 53 and 55 may be in the same direction as the prior shifting of such respective members.

On the other hand, if the nozzles 97 moved through an angle of only 180 during each turning thereof the strands in the resulting netlike structure will be disposed in a woven or braided relationship. As long as there is no change in the direction of turning of the nozzles 97, no change is necessary in the direction of shifting of the respective annular members 53 and 55. if, however, the nozzles 97 are turned in a direction opposite to their immediately prior turning movement, then it is essential that the directions in which the annular members 53 and 55 are shifted be opposite to that of their immediately prior movement.

As can be seen from the above description, in the manufacture of tubular netlike structures the method practiced with the apparatus of the present invention can be varied considerably, as by shifting the member 53 and/or the member 55, by varying the angle through which such members are shifted and by changing the directions in which the nozzles 97 and members 53 and 55 are moved. These variations in the method will, of course, provide for different strand patterns in the resulting netlike structure.

When making netlike structures of a curved configuration which is less than 360, the member 53and/or the member 55 may be shifted and the angle through which such members are moved may be varied to some degree. However, in the manufacture of such curved netlike structures it is essential that only complete nozzles 97 be turned and that their direction of turning be reversed after the member 53 and/or the member 55 is shifted. Likewise, the direction in which the member 53 and/or 55 is shifted must also be reversed after each turning of complete nozzles 97.

For example, the support members 53 and 55 may be pro vided with recesses 93 and 95 at spaced intervals along only a l80 arc of their respective peripheries 89 and 91. When such recesses 93 and 95 are aligned, circular openings are provided within each of which is disposed a nozzle 97. With flowable strand-forming material being extruded from each of the extrusion section orifices, the nozzles 97 are all turned 180 in one direction about their respective axes. Either of the members 53 and 55 is then shifted, for example a distance equal to the angular spacing between nozzles 97 as measured along the peripheries of the members 53 and 55. Alternatively the members 53 and 55 may be shifted in opposite directions a distance equal to one-half of the angular spacing between nozzles.

As a result of this latter movement, an extrusion section 103 of each of the outermost nozzles of the series of nozzles 97 are, in effect, moved in opposite directions relative to each other and no longer form part of complete nozzles 97. The complete nozzles 97 are now turned 180 about their respective axes but in a direction opposite to their prior turning. f course, in such embodiment teeth would be omitted from along those portions of the ring gears 125 and 127 which are adjacent to the nozzles sections 103 which are not part of complete nozzles 97. Once turning of the complete nozzles is effected, either one or both of the members 53 and 55 are shifted but in a direction opposite to their prior movement.

In making netlike structures of tubular construction or of a 113 in the nozzle extrusion sections 103 of course follow like paths and when set provide a netlike structure having strands which are interlaced in a woven or braided relationship. As heretofore mentioned, the extruded streams of strand-forming material may be set before or after they have contacted each other, depending upon the characteristic, such as flexibility, strand stability, etc. desired in the finished structure.

I claim:

1. Apparatus for making a curved netlike structure by extrusion including a plurality of composite nozzles each including a pair of like extrusion sections and a spacer section positioned therebetween, the extrusion and spacer sections of each nozzle having mating arcuate walls with the arcuate walls with the arcuate walls of all extrusion sections being of like radius, means supporting said nozzles in spaced-apart relationship with an arcuate wall of each nozzle extending along a common arc having a radius equal to that of said arcuate walls, means for intermittently turning nozzles through an angle of only l80 or further multiple of 180 about an axis located midway between the arcuate walls of the extrusion sections thereof, means operative alternately with said turning means for relativelymoving the extrusion sections of each of said nozzles to rearrange the same into alignment with like extrusion sections of other of said nozzles, with corresponding extrusion sections of the respective nozzles being moved simultaneously and in the same direction along a path concentric with the common are, an orifice extending through each of said extrusion sections, means for delivering flowable strand-forming material to each of said orifices, and means for setting the flowable strand-forming material extruded from said orifices.

2. An apparatus as defined in claim 1 wherein the arcuate walls of the extrusion sections of at least one pair of nozzles are of convex configuration.

3. An apparatus as defined in claim 1 wherein the arcuate walls of the extrusion sections of at least one pair of nozzles are of concave configuration.

4. Apparatus as defined in claim 1 wherein the arcuate walls of all of said extrusion sections are of like configuration.

5. Apparatus as defined in claim 1 wherein said nozzle supporting means includes a pair of concentric annular member, one of which is disposed with its outer peripheral surface slidably engaging with the inner peripheral surface of the other thereof, and cooperating recesses formed along said peripheral surfaces for together rotatably supporting said nozzles.

6. Apparatus as defined in claim 5 wherein said means for relatively moving the extrusion sections of each of said nozzles includes means for driving at least one of said annular members in the same direction alternately with the operation of said turning means.

7. Apparatus as defined in claim 5 wherein said means for relatively moving the extrusion sections of each of said nozzles includes means for oscillating at least one of said annular members and wherein said turning means oscillates each nozzle, with the movement of said annular member in one direction alternating with the turning of each nozzle in one direction.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,60l,850 Dated August 31, 1971 InVentor(s) Theodore H. Fairbanks It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 1, line 61, after "by" and before "continuous" insert the following, -continuously repeating the above sequence of movements, with the ---7 line 62 "and" should read -a--; line 66, "not" should read -nor-. Col. 2, line 62, "on" should read -one-; line 70 after "the" and before "extrusion" (on line 71) insert --arcuate walls of the extrusion sections are of convex configuration and/or at least one pair of nozzles in which the-. Col. 3 line 16, after "formed" insert with--. C01. 4, line 5, "and" should read an-; line 29, "tow" should read -two-; line 36, "arcuated" should read --arcuate-; line 4-1, after "drawing, and before "pair" insert -each; lines 63 through 64, after "capable" and before "providing" insert -of-. Col. 6, lines 29 and 30, after "extrusion" and before "sections" delete -members 53 and 55 to rearrange or pair the respective extrusion--; line 39, after "the" and before "member" (first occurrence)- insert -annular-;

line 39, after "member (first occurrence) and before "and" insert 53; line 64 "extrusions" should read --extrusion sections. Col. 7 line 8, "with" should read which-. Col. 8, Claim 5, line 53, "member" should read -members-.

Signed and sealed this 7th day of March 1972.

(SEAL Attest:

EDWARD M.FLETC HER,JR. ROBERT GO'I'TSCHALK Abtesting Officer- Commissioner of Patents )RM PO- 0 USCOMM-DC 6O37B-P69 U 5 GOVERNMENT PRINTING OFFICE 1 1969 O-36B-334 

1. Apparatus for making a curved netlike structure by extrusion including a plurality of composite nozzles each including a pair of like extrusion sections and a spacer section positioned therebetween, the extrusion and spacer sections of each nozzle having mating arcuate walls with the arcuate walls with the arcuate walls of all extrusion sections being of like radius, means supporting said nozzles in spaced-apart relationship with an arcuate waLl of each nozzle extending along a common arc having a radius equal to that of said arcuate walls, means for intermittently turning nozzles through an angle of only 180* or further multiple of 180* about an axis located midway between the arcuate walls of the extrusion sections thereof, means operative alternately with said turning means for relatively moving the extrusion sections of each of said nozzles to rearrange the same into alignment with like extrusion sections of other of said nozzles, with corresponding extrusion sections of the respective nozzles being moved simultaneously and in the same direction along a path concentric with the common arc, an orifice extending through each of said extrusion sections, means for delivering flowable strand-forming material to each of said orifices, and means for setting the flowable strand-forming material extruded from said orifices.
 2. An apparatus as defined in claim 1 wherein the arcuate walls of the extrusion sections of at least one pair of nozzles are of convex configuration.
 3. An apparatus as defined in claim 1 wherein the arcuate walls of the extrusion sections of at least one pair of nozzles are of concave configuration.
 4. Apparatus as defined in claim 1 wherein the arcuate walls of all of said extrusion sections are of like configuration.
 5. Apparatus as defined in claim 1 wherein said nozzle supporting means includes a pair of concentric annular member, one of which is disposed with its outer peripheral surface slidably engaging with the inner peripheral surface of the other thereof, and cooperating recesses formed along said peripheral surfaces for together rotatably supporting said nozzles.
 6. Apparatus as defined in claim 5 wherein said means for relatively moving the extrusion sections of each of said nozzles includes means for driving at least one of said annular members in the same direction alternately with the operation of said turning means.
 7. Apparatus as defined in claim 5 wherein said means for relatively moving the extrusion sections of each of said nozzles includes means for oscillating at least one of said annular members and wherein said turning means oscillates each nozzle, with the movement of said annular member in one direction alternating with the turning of each nozzle in one direction. 